Version 7 brings a major rewrite to Internet Information Server. The most important of these revolves around the new integrated mode, which allows .NET modules to be plugged into any stage of the IIS pipeline. However, when running ASP.NET in integrated mode reveals several breaking changes.
- Traditional HTTP Modules and Handlers have to be reconfigured in the web.config files.
- Impersonation in the BeginRequest and AuthenticateRequest stages are no longer supported.
- Applications can no longer use both Forms and Windows Authentication at the same time.
- Non-standard HTTP clients may have problems using Windows Authentication because of how authentication has been moved into the kernel.
- Other authentication issues revolve around timing such as when client impersonation comes into play.
- The global event DefaultAuthentication_OnAuthenticate method is no longer supported and the event WindowsAuthentication_OnAuthenticate won't always be fired.
- Passport authentication has been completely deprecated. Unlike all of the previous breaking changes, there is no workaround for this one. Passport isn't even available when running IIS in classic mode.
To see the full list of breaking changes look at Mike Volodarsky's post.